U.S. Pat. No. 3,292,427, issued to W. S. Mattson on Dec. 20, 1966, for an "Analysis Apparatus," discloses a cooling system instrument for use in analyzing problems in automotive cooling systems. U.S. Pat. No. 3,292,427 is incorporated herein by this reference thereto. The disclosed invention comprises an instrument module 10A intended for insertion between a cooling outlet of an internal combustion engine block and an inlet to the automotive cooling radiator. See, FIGS. 1 and 2. The instrument module of the U.S. Pat. No. 3,292,427 includes a flow meter 16 for measuring the flow rate of the engine coolant, and a combination temperature and pressure gauge 32. These three gauges, as incorporated into instrument module 10A, enable one of ordinary skill in the art of cooling system analysis to diagnose almost any engine cooling problem with a high degree of accuracy. However, when the instrument module is inserted into the automotive cooling system, air is entrapped in the system and must somehow be removed before accurate testing may begin.
Subsequent to the filing date of the U.S. Pat. No. 3,292,427, instrument module 10A of the invention there disclosed was modified in an embodiment incorporating two piece transparent plastic moldings (see, FIG. 5, as shown, but without items identified by reference numerals 12 and 14) which served all of the purposes of the module disclosed in the U.S. Pat. No. 3,292,427. This modification allowed an operator to visually sense presence of air in the system by observing air bubble flow in the transparent module.
However, both the system of the prior art invention disclosed in U.S. Pat. No. 3,292,427, and the later version, explained above, suffer from lack of a convenient way to bleed the air out of the cooling system subsequent to the insertion of the instrument module of the '427 patent into that cooling system. Therefore, it is frequently the case that some air is left in the system and air interferes with the operator's ability to get valid information from the system. The undesirable air may be confused by the operator with undesirable aeration by reason of a resident fault in the system under test. For example, if there is already air in the unheated cooling system, it makes it more difficult to discern the presence or collection of any additional air leaking into the system; such as air which may be introduced after engine shut-down by reason of a leak anywhere in the automotive cooling system. This may occur because the system coolant is contracting as the temperature of the coolant is reduced, or by reason of a leak on the suction side of the engine coolant pump during engine operation at normal or excessive operating pressures and temperatures. Extraneous air in the system may also cause problems in reading the flow meter and might affect temperature and pressure readings on the module gauges.
And, finally, aeration of the system may have a detrimental effect on the efficiency of the cooling system, a characteristic which the operator of the instrument is attempting to analyze, thereby yielding erroneous results.